这个问题通常是因为Agora启动方法的post参数无效或格式不正确导致的。解决方法是检查参数并确保其正确性。以下是一个使用Agora开发SDK的示例代码，您可以参考这个代码来检查您的参数是否正确：

Agora agora = new Agora(APP_KEY);
String channel = "testchannel";
String uid = "testuid";
String token = "testtoken";
String mode = "rtc";
String codec = "h264";
String role = "host";
int audienceLatencyLevel = 1;	
boolean videoMute = false;	
boolean audioMute = false;	
boolean enableDualStream = false;	
boolean enableEncryption = false;	
boolean enableSimulcastStream = false;	
boolean enableBackgroundRecording = false;	
boolean enableBeautyCam = false;	
String transcodingUsers = "user1,user2";
String transcodingConfig = "{...}"; // Transcoding configuration string

JSONObject params = new JSONObject();
params.put("channel", channel);
params.put("uid", uid);
params.put("token", token);
params.put("mode", mode);
params.put("codec", codec);
params.put("role", role);
params.put("audienceLatencyLevel", audienceLatencyLevel);
params.put("videoMute", videoMute);
params.put("audioMute", audioMute);
params.put("enableDualStream", enableDualStream);
params.put("enableEncryption", enableEncryption);
params.put("enableSimulcastStream", enableSimulcastStream);
params.put("enableBackgroundRecording", enableBackgroundRecording);
params.put("enableBeautyCam", enableBeautyCam);
params.put("transcodingUsers", transcodingUsers);
params.put("transcodingConfig", transcodingConfig);

agora._post("/v1/channel/start", params);

请确保您的参数与上述代码一致，如果还有问题，请检查Agora文档或联系Agora支持团队来获取更多帮助。